#include <iostream>
using namespace std;

// 206. 反转链表
// 给你单链表的头节点 head ，请你反转链表，并返回反转后的链表。
// https://leetcode.cn/problems/reverse-linked-list/description/

// Definition for singly-linked list.
struct ListNode {
    int val;
    ListNode *next;
    ListNode(): val(0), next(nullptr) {}
    ListNode(int x): val(x), next(nullptr) {}
    ListNode(int x, ListNode *next): val(x), next(next) {}
};
// 递归方法
class Solution {
public:
    ListNode* reverseList(ListNode* head) {
        if(head == nullptr || head->next == nullptr)
            return head;

        ListNode* newHead = reverseList(head->next);
        head->next->next = head;
        head->next = nullptr;

        return newHead;
    }
};
int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}
